The search for fresh or potable water remains a pressing concern throughout many regions of the world, even though most of the Earth's surface is covered by oceans. The World Health Organization (WHO) reported that about 41% of the Earth's population lives in water-stressed areas and the number of people in the water scarce regions may climb to 3.5 billion by the year 2025. Hence, there is a great motivation to explore a more efficient and environmental-friendly desalination method.
The methods for desalination available hitherto are categorized into two groups, namely, the thermally and the electric power-driven methods. The thermal activated process includes multi-stage flash (MSF) and multi-effect desalination (MED) whereas the second method includes membrane-based reverse osmosis (RO), freezing, mechanical vapor compression and electro-dialysis. The hybrid plants are a combination of the RO and the MSF processes and they can recover higher water yields of water with lesser dissolved solids (<500 mg/l) for human consumption, as stipulated by the World Health Organization (WHO) standards. Ion exchange is another hybrid method whereby ions of dissolved inorganic salts are replaced with the more desirable ions, and such as a process have been used to minimize the fouling and carry-over to the water. The aforesaid types of desalination suffer from three fundamental drawbacks: (i) The high thermal energy consumption as the processes are maintained at higher driving source temperatures, (ii) the high electric energy consumption due to the poor recovery ratios and (iii) the high maintenance cost arising from salt deposition, fouling in the evaporating unit or the frequent replacement of membranes.